The OEOptimizer0 abstract class defines the interface for
optimizing a set of variables for which a function can be evaluated.
Implementations of OEOptimizer0 use only function values during
optimization, so it does not calculate gradients.

These methods define the interface for optimizing a set of variables
with the use of evaluated function values. The reference to the function object
is passed as a first argument. Initial values of variables are passed in the
array var. The optimized variables are returned in the array opt_var.
Both operators return the value of the corresponding optimized function value.
The second operator takes a pointer to the OECheckpoint0 object
that can be used to monitor the progress of an optimization.

Defines the interface for setting the maximum number of iterations that an
optimizer derived from the OEOptimizer0 will attempt while
trying to identify a converged minimum function value. Optimization will cease if
the iteration limit is reached without finding a converged minimum.